An aromatic polycarbonate resin is used as a material for manufacturing various molded articles in a wide variety of fields, making use of its transparency and impact resistance. In the application field of this aromatic polycarbonate resin, nowadays, attention is paid to flame retardancy at the time of a fire, and a resin composition having high flame retardancy besides the above characteristic properties is desired. To provide flame retardancy to an aromatic polycarbonate resin, there is proposed a flame retardant resin composition comprising a halogen-based compound or a phosphorus-based compound. This resin composition is used in OA equipment and home electric appliances which are strongly desired to be flame retardant. Further, a silicone-based flame retardant is proposed and attracts attention as a material having a low environmental load.
A large number of technologies for flame retarding an aromatic polycarbonate resin are proposed. One of them is, for example, a method in which an organic metal salt is added to flame retard an aromatic polycarbonate resin (see to Patent Documents 1 and 2). Since the application field of a flame retardant aromatic polycarbonate resin material is diversified, further improvement of flame retardancy is desired.
To improve flame retardancy, there is proposed a method in which flame retardancy is improved by adjusting the quality of a conventionally known flame retardant to a suitable range and not by changing the type of a flame retardant or increasing the amount of a flame retardant. For example, for an aromatic polycarbonate resin composition comprising a fluorine-containing organic metal salt compound typified by an alkali metal salt of a perfluoroalkylsulfonic acid, there is proposed (i) a method in which the pH of an aqueous solution or dispersion of the compound is adjusted to 5 to 9 (see Patent Document 3). Further, there is known (ii) a method in which the alcohol insoluble content of the compound is reduced (see Patent Document 4). However, these proposals are interesting in a sense that the factor of reducing flame retardancy is clarified but fail to clearly distinguish the above composition from commercially available fluorine-containing organic metal salt compounds. Although various additives are added to a polycarbonate resin for practical use in most cases, a method of achieving excellent flame retardancy without impairing an effect expected from the addition of the additives is not made clear. A manufacturing process in which the content of a fluoride ion in an alkali metal salt of a perfluoroalkylsulfonic acid is set to 1 ppm is known (see Patent Document 5). However, a combination of an alkali metal salt of a perfluoroalkylsulfonic acid obtained by the above manufacturing process and an aromatic polycarbonate resin is unknown.
Patent Document 1JP-B 54-32456Patent Document 2JP-B 60-19335Patent Document 3JP-A 2001-31855Patent Document 4JP-A 2001-115004Patent Document 5JP-A 1-268671